PUPatternTextField.swift

//
//  PUPatternTextField.swift
//  PeixeUrbano
//
//  Created by Guilherme Rambo on 24/01/17.
//
//

import UIKit

/// A text field that can have its input masked using a `MaskPattern`
open class PUPatternTextField: UITextField {
    
    public var textChangeHandler: ((String) -> ())?
    public var programmaticTextChangeHandler: ((String) -> ())?
    
    /// Mask pattern to be applied to the field's input
    public var pattern: MaskPattern? {
        didSet {
            // reapply pattern when changed
            let textBeforePatternChange = self.inputText
            self.inputText = textBeforePatternChange
        }
    }
    
    /// Use this property to set the input's text programmatically
    public var inputText: String? {
        didSet {
            text = inputText
            
            if !isUserEditing {
                programmaticTextChangeHandler?(rawInput)
            }
        }
    }
    
    /// This property stores the raw input string, without the pattern applied to it
    public var rawInput: String {
        if let filter = pattern?.filter {
            return filter.closure(text ?? "")
        } else {
            return text ?? ""
        }
    }
    
    private var isUserEditing = false
    
    override public init(frame: CGRect) {
        super.init(frame: frame)
        
        registerObserver()
    }
    
    required public init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        
        registerObserver()
    }
    
    private func registerObserver() {
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(textDidChange),
                                               name: NSNotification.Name.UITextFieldTextDidChange,
                                               object: self)
    }
    
    @objc private func textDidChange() {
        isUserEditing = true
        
        processTextInput()
        
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
            self.isUserEditing = false
        }
    }
    
    private func processTextInput() {
        guard let pattern = pattern else { return }
        guard let inputText = text, inputText.characters.count > 0 else { return }
        
        self.text = pattern.apply(to: inputText)
        
        textChangeHandler?(rawInput)
    }
    
    deinit {
        NotificationCenter.default.removeObserver(self)
    }
    
}